The South African State of Rivers Report: uMngeni River and Neighbouring Rivers and Streams

RHP

South African
River Health Programme

State of the Rivers Report
uMngeni River and Neighbouring Rivers and Streams

WHY IS IT IMPORTANT TO KNOW ABOUT RIVER HEALTH?

People need rivers. Human and economic well-being are directly or indirectly dependent on the goods and services provided by river systems. For example, we obtain drinking water and water for irrigating crops from rivers, we may fish, harvest reeds, have picnincs on the riverbanks or perform baptisms in the river pools. Some goods and services provided by rivers are important for human survival, such as water for drinking and subsistence fishing. Other uses of goods and services support social needs (e.g. agricultural and industrial production).

Some goods and services may be lost, or reduced in diversity, quality and/or quantity, when a river system is impaired. The sustained use of a range of goods and services is therefore, directly dependent on the ecological health of the river. (The term "rive health" simply refres to the condition of a river, in the same way as health would refer to the condition of a person or an economy). in order to protect our ability to use and benefit from river goods and services over the long term, we must look after the health of our rivers and their ability to provide these goods and services.

Why do we need this report?

Information about river health tells us about the range and quality of goods and services that a particular state of the river system can deliver. It also tells us about the sorts of impacta that a river system can absorb. This information helps us to manage our rivers because with an understanding of river health we can set goals and decide on action steps for achieving a desired river state that would ensure the provision of a preferred range and quality of goods and services. River health information collected over a period of time also allows us to track changes in river health and therefore our progress towards (or away from) a defined goal.

Why be involved?

Mnay aspects of our survival and economic growth are critically affected, directly or indirectly, by the health of our rivers and by the decisions that change their ability to deliver a range of goods and services. Therefore, the decisions around what we want and need from our rivers and the way we share the benefits, should be made jointly. In order to make informed decisions, we need appropriate and trusted information. It is in the field of river health monitoring and reporting that the River Health Programme contributes to informed decision-making in support of sound river management.

THE RIVER HEALTH PROGRAMME

Background

The Department of Water and Sanitation (DWAF) is the custodian of our country's water resources. This responsibility includes the protection of the ability of river ecosystems to continue to provide goods and services, and in doing so, to protect their use and associated benefits for current and future generations. As a result, DWAF initiated the River Health Programme (RHP) in 1994.

What is the objective of the RHP? This programme is designed to develop a capacity and information base to enable us to report on the ecological state of our rivers, in an objective and scientifically sound manner. At the same, through river health reporting, the programme aims to be explicit in identifying areas of sustainable utilisation and also to flag areas where deterioration of the river system is causing undesirable changes in the delivery of goods and services.

What does the RHP do? The programme generates information which is based on the assessment of the condition od biological communities in and around rivers (such as fish, aquatic invertebrates, riparian vegetation and river habitats). Together, they provide an integrated measure of the health of river systems.

A collaborative venture

The River Health Programme consists of partnerships that are critical for the success of the programme. At the national level, DWAF plays the lead role while the Department of Environmental Affairs and Tourism (DEAT) and cthe Water Research Commission (WRC) are key partners. RHP activities are co-ordinated at a provincial level where collaboration plays an important role. Each province has a network of implementers who work together, usualy under the leadership of a Provincial Champion.

Through actively working together and sharing skills and resources, implementation teams can achieve goals that would not be possible for any one organisation working alone. The implementation team for KZN was elected at an open workshop in 1997. A cross-section of organisations have contributed since then, including the DWAf, the Town and Regional Planning Commission, Umgeni Water, The Umlaas Irrigation Board, Richards Bay Minerals, eThekwini Municipality, Mhlatuze Water, Universities of Zululand and Natal, KZN Wildlife, Farmer Support Group (Ntshogweni Catchment Project), CSIR and Alletson Ecologicals.

Legal Context of the RHP

TThe equitable, efficient and sustainable use of our water resources is the central objective of South Africa's water policy. The National Water Act (1998) recognises that the best way to achieve this would be to manage aquatic ecosystems (including rivers) at the catchment scale and through joint participation by all interested parties. The RHP supports this management process by providing river health information that will be needed by both managers and the participating public to make decisions.

Although the RHP is not specifically mandated by any South African act or parliament, RHP activities and outputs are strongly aligned with legal requirements: The Water Act requires that the health of aquatic ecosystems is monitored and the RHP monitoring results can in turn, be used to support certain legal principles contained in the National Environmental Management Act (NEMA) and the National Water Act. For example, RHP results can be used to support evidence of environmental degradation. The law also requires that river protection measures should take into account the characteristics of in-stream and riparian vegetation as well as the characteristics and distribution of aquatic plants and animals.

The RHP also supports the NEMA which is largely concerned with governing the sustainable use of the environment and the protection of ecosystems (including rivers). The act calls for information about the current state of ecosystems as well as changes in state over time, indicating where environmental impacts are occurring and providing guidance for the planning future developments.

MEASURING RIVER HEALTH

Many factors influence the health of a river ecosystem: viz. geomorphological characteristics, hydrological and hydraullic processes, chemical and phydical water quality and the nature of instream and riparian habitats. Measuring each of these in detail would be impractical. The RHP therefore focuses on selected ecological indicator groups that are representative of the larger ecosystem and are feasible to measure. In this way, complex data, collected for each indicator group, can be summarised and expressed in a format that is easy to understand. The following indices were used to assess the health of the uMngeni and neighbouring rivers:

WATER QUALITY INDEX - The index is based on data collected by Umgeni Water and eThekwini Municipality as part of their routine monitoring programmes. The index combines a range of water quality variables that are the most useful for indicating deteriorating water quality, and which indicate most clearly the potential for obtaining goods and services from this water. Variables included in this index are E. coli (indicating degree of faecal contamination), turbidity, conductivity, nitrate, ammonia, total and soluble forms of phosphorus, suspended solids and total organic carbon.

INDEX OF HABITAT INTEGRITY (IHI) Habitat availability and diversity are major determinants of the suite of fuana anf flora found in a specific ecosystem. Therefore, knowledge of the qaulity of habitats is very important in an overall assessment of ecosystem health. The IHI is designed to assess the impact of major disturbances on river ecosystems. Disturbances include water abstraction, flow regulation and river channel modification. The index accounts for both the condition of the riparian zone and instream habitats.

Riparian zone - This provides habitat for aquatic and terrestrial species, contributes towards maintaining the form of the river channel and serves as filters for sediment, nutrient and light. The structure and function of riparian vegetation are altered with vegetation removal, cultivation, construction, inundation, erosion, sedimentation and invasion by alien vegetation within or close to the riparian zone.

Instream habitat - This will vary depending on the substrate, with awide diversity of organisms, although some rivers are naturally poor in habitat diversity. Distrubances include excessive sedimentation or scouring of the river bottom, alteration of the water quality by the addition of contaminants, and changes in the natural flow regime of the river due to the presence of dams and/or major abstractions.

The IHI assessment of the uMngeni catchment was not conducted using the full method due to cost constraints. The method used was a "desktop" method that made use of expert local knowledge to answer a range of questions forming a matrix, from which the IHI score was derived.

SOUTH AFRICAN SCORING SYSTEM (SASS) - index for aquatic invertebrates - A variety of invertebrate orgsnisms (e.g. insect larvae, snails, crabs, worms) require specific aquatic habitat types and water quality codnitions for at least part of their life cycle. Changes in the composition and structure of aquatic invertebrate communities are signs of change in overall river condition. As most invertebrates are relatively short-lived and remain in one area during their aquatic life phase, they are particularly good indicators of localised conditions in a river over the short term (months). The SASS is a relatively simple index that is based on the families of aquatic invertebrates present at a site.

FISH ASSEMBLAGE INTEGRITY INDEX (FAII) - Fish, being realtively long-lived and mobile, are good indicators of long term influences on a river reach and the general habitat conditions within the reach.The number of species of fish that occur in a psecific reach, their sensitivity to various forms of disturbances as well as factors such as different size classes and the condition of fish, can be used as indicators of river health. The FAII integrates such characteristics of a fish assemblage. The output of the FAII is an expression of the degree to which a fish assemblage deviates from what would have been expected in the absence of human impacts.

Fish data for the uMngeni catchment were unfortunately not in a format that could be used for the proper implementation of the FAII and no monitoring programmes have yet been implemented for fish assessment in the catchment. As a result, a simpler method had to be used. This "bench-top" method assessed existing (historical) knowledge of the diversity of species and fish habitats, the presence of important or rare species, in a matrix that gave an overall score. The information used was not always current, so recent changes in fish population may have been missed.

RIVER HEALTH CLASSIFICATION

Once river health indices are measured, they need to be interpreted within a framework that allows us to compare the health of one monitoring site (or river system) with another. An ecoregion classification system was used to delineate ecological boundaries that allow us to assess the health of the uMngeni and uMlazi Rivers.

Ecoregions are rgions of broad ecological similarity. In other words, rivers that occur within a particular ecoregion will be more similar to each other than to rivers in other ecoregions. For example, the Midmar Dam resources unit in this report (p.14) is divided into two regions, an upper and lower. These are two distinct ecoregions. Variation in natural characteristics such as, climate, geology, physiography and vegetation as well as riover habitat and the distribution of biota, was used to delineate the ecoregions. Because they present units of ecological similarity, ecoregions provide convenient boundaries within which to do ecological assessments and to set goals for an improved state of the river ecosystem.

River Health Classes

The results that are obtained by applying the biological and habitat indices during a river survey provide the information for determining the health of the river. In order to standardise the output of the different indices as well as to allow comparison of the health of different river systems, a river heaslth classification is used. Each index is calibrated so that its results can be expressed as a river health class.

River health classes can be expressed in terms of ecological and management perspectives.

Each of the river health classes is associated with a level of ecosystem health, and the potential to offer a particular range of goods and services. For example, a section of river in Natural Class may be most suitable for conservation and tourism, and even though it could be used for agriculture, the socio-economic returns on the latter activity might be much smaller compared to the conservation and tourism option. Similarly, a choice could be made whether to use a Good Class river as a source of drinking water, or for agriculture, or for tourism, or some combination of these. A river in the Fair Class may have lost its capacity to serve some of these potential users. An example may be a river that contains salt pollution as a result of providing service to industry. This river would no longer be ideal for use by agriculture, but this may be considered as acceptable from management point of view. In the Poor Class, a river's ability to provide a wide range of goods and services to a range of users is severely compromised. For example, while highly polluted river continues to provide a service to industry in getting rid of its waste, the detrimental effects of this pollution to others may be unacceptable.

Each river health class reprsents a comdination of human impacts. We need to make decisions around these impacts knowing that:

our choices affect the state of the river ecosystem and its ability to deliver specified benefits;

our choices around goods and services affect the opportunity for others to benefit (e.e. there is always a trade-off);

our choices may affect the opportunity for future generations to benefit; and

the impacts of our choices cannot necessarily be reversed - easily, or at all.

Each one of our activities within a catchment, indirectly or directly drive changes in river health. It is only when we start to understand how our own and other's activities affect rivers and their ability to provide us with benefits, that we will be able to make wise and fair trade-offs around the mixture of impacts and benefits that will be acceptable to the catchment community.

RIVER HEALTH CLASS	ECOLOGICAL PERSPECTIVE	MANAGEMENT PERSPECTIVE
Natural	No or negligible modification of in-stream and riparian habitats and biota.	Protected rivers, relatively untouched by human hands; no discharge or impoundments allowed.
Good	Ecosystems essentially in good state; biodiversity largely intact.	Some human-related disturbance but mostly of low impact potential.
Fair	Sensitive species may be lost; lower abundances of biological populations are likely to occur, or sometimes, higher abundances of tolerant or opportunistic species occur.	Multiple disturbances associated with need for socio-economic development, e.g. impoundment, habitat modification and water quality degradation.
Poor	Habitat diversity and availability have declined; mostly only tolerant species present, species present are often diseased; population dynamics have been disrupted (e.g. biota can no longer reproduce or alien species have invaded the ecosystem).	Often characterised by high human densities or extensive resource exploitation. Management intervention is needed ti improve river health - e.g. to restore flow patterns, river habitats or water quality

STATE-OF-RIVERS (SoR) REPORTING

State of the Environment (SoE) reporting, led by DEAT, has developed over the past decade in response to a need for appropriate information to assist with environmental decision-making. The national SoE for South Africa uses the Driving Force-Pressure-State-Impact-Response framework to explain what is causing environmental change, how good or bad the conditions are and what we can and are doing about it.

In response to the need for improved environmental reporting, this State-of-Rivers (SoR) report, the third one of a series, is designed to

assist ecologically sound management of the uMngeni and its neighbouring rivers, so that these rivers can deliver an optimal range of goods and services to people, and

inform and educate the people of South Africa about the state of health of these rivers and the importance of ensuring sustained benefits from them through wise management.